Hydraulic table reciprocating mechanism



v Jl-me 9- B.- H. GOEI'I-IRING 2,161,156

HYDRAULIC TABLE RECIPRCCATING MECHANISM I Filed March 8, 1938 2 Sheets-Sheet 1 EERNHHRJJ H. GUEHR/NE June 1939- 1 I B. H. GO-EHR-ING 2,161,156

HYDRh'ULIC TABLE RECIPROCATING MECHANISM Filed March 8, 1938 2 Sheets-Sheet 2 I25 7 I00 11.? i1 2 7 Fl'g5 I V WW BERNHHRD H. Gu HR/NG Patented June 6, 1939 UNITED STATES PATENT OFFICE HYDRAULIC TABLE RECIPROCATING MECHANISM Application March s, 1938, Serlal No. 194,610 Claims. ((11. 121-45) The invention relates to grinding machines, and more particularly to a table reciprocating mechanism for a grinding machine.

One object of the invention is to provide a simple and thoroughly practical table reciprocating and reversing mechanism. Another object of the invention is to provide a table reversing mechanism with an improved dwell control mechanism. Another object of the invention is to provide a table reversing mechanism with a mechanism whereby a variable dwell may be obtained at either or both ends of the table reciprocation. A further object of the invention is to provide an electrically controlled dwell control for a table reciprocating mechanism. A further object of the invention is to provide a hydraulically operated table reciprocating mechanism with an electrical time delay relay, control therefor to control the extent of dwell at each end of the table stroke. ,Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and

the scope of the application of which will beindicated in the following claims.

In the accompanying drawings in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. 1 is a combined hydraulic and electrical diagram of the improved table reciprocating mechanism;

Fig. 2 is a cross sectional view through the table reciprocating mechanism, showing the valve actuating mechanism in cross section;

Fig. 3 is a longitudinal sectional view, on an enlarged scale, taken approximately on the line 3-3 of Fi 2;

Fig. 4 is a sectional view taken approximately on the line 4-4 of Fig. 3; and

Fig. 5 is a fragmentary view showing the V-shaped port 54.

As illustrated in the drawings, the machine em- 45 bodying this invention comprises a base 9 which supports a longitudinally reciprocable table ID on the usual V-way and fiat way (not shown) for a longitudinal reciprocatory movement relative to the base 9.

A fluid pressure operated reciprocating mechanism is provided to reciprocate the table In, comprising a fluid pressure cylinder H which is fixedly mounted to the under side of the table ill. The cylinder l I contains a pair of spaced pistons l2 and I3 which are connectedby a pair of hollow piston rods I4 and I5, respectively, with a pair of hollow brackets l3 and II, respectively, mounted on opposite ends of the base 9.

In the preferred construction, the base 9 is formed with a hollow box-like construction, in which the lower portion serves as a reservoir 20 for the fluid pressure system. Fluid is drawn from the reservoir 23 through a pipe 25 by a motor driven fluid pressure pump 22 and is forced through a pipe 23 and a pipe or passage 24 to a table control valve 25. A fluid pressure relief valve 26 is provided in the pipe line 23 and is arranged to allow excess fluid under pressure to by-pass through a pipe 21 into the reservoir 22 in case the pressure within the system increases above a desired predetermined pressure.

A control valve 2! is preferably of a piston type reversing valve which includes a movable valve member 29 having formed integrally therewith a I plurality of valve pistons 30, 3|, 32, 33 and 34.

Fluid under pressure from the pump 22 is forced through the pipes 23 and 24 into a valve chamber 31, between the valve pistons 3| and 32, and passes outwardly through a pipe 39 into an aperture 40 in bracket I6, through the 'hollow piston rod l4 and piston I2, into a cylinder chamber 4| to cause the cylinder II and table III to move in a direction toward the left (Fig. 1). During movement of the table toward the left, fluid within a cylinder chamber 42 is exhausted through the piston l3, the hollow piston rod, an aperture 33 within the bracket l1, and through a pipe ll into a valve chamber 33 -between the valve pistons 32 and 33, and out throughapipe 45 which returns exhaust fluid through a pipe 46 into the reservoir 20.

A speed control valve 50, as illustratedin the drawings, is preferably formed integralwith the valve 25. As illustrated in the diagram (Fig. 1). the valve is shown as a separate valve unit. The valve 53 is preferably located in the exhaust side of the system so as to maintain a uniform fluid pressure on the operative side of the main cylinder. This valve comprises a valve stem 5! which is provided with valve pistons 52 and 53. The casing for the valve is provided with a V- shaped port 54 which is located at one end of the pipe line or passage 45, conveying fluid from either the valve chamber 31 or 39, depending upon the position of the valve 25. The passage or outlet pipe 48 serves to exhaust fluid. from a throttle valve chamber 5'! into the reservoir 26) within the base of the machine.

The throttle valve ill is arranged so that it may be moved'longitudinally from a full line to with an actuating knob 59 on the front end of the valve stem 5| which facilitates rotation of the valve. the valve piston 53, instead of being a plane surface at right angles to the axis of the throttle valve, is arranged at an angle thereto. By providing an angularly positioned end surface on the valve piston 53, any rotation of the valve member serves as a fine adjustment to cut oii more or less of the V-port- 54 precisely to regulate the exhaust of fluid from the system and thereby permit a fine regulation of the table speed.

In order that the valve piston 53 may be maintained in the desired adjusted position so as to enable the table to be stopped and started as desired, without changing the speed adjustment, a serrated or notched portion 59 is provided which is formed integral with the valve stem 5|. A spring pressed pawl 6| is carried by the valve casing 59 so that when the knob 59 is rotated to adjust the valve piston 53 to give the desired table speed, the detent 6| engages notches in the serrated portion 69 and serves to hold the valve piston in its adjusted position so as to permit longitudinal or axial movement of the valve stem 5| by means of a control lever I9 to stop and start the table movement without upsetting the speed adjustment of the valve.

The control lever I9 is pivotally mounted on a stud I| fixedly mounted on the base 9 of the machine and serves to permit a rapid movement of the valve stem 5| to stop and start the table movement. The lever I9 is provided with an aperture I2 fitting loosely around a sleeve I3 which is mounted on the valve stem 5|. A pair of opposed aligned trunnion pins 14 are. provided at opposite sides of the aperture I2 on the lever I9 and are arranged to engage vertical slots I5 in the sleeve I3. It will be readily apparent from the foregoing disclosure that when the throttle valve lever is in the position indicated in full lines, the valve stem 5| is positioned so that the valve piston 53 uncovers all or a portion of the V-port 54, allowing the table to move at a predetermined speed. By moving the lever I9 into position Illa, as indicated in broken lines in Fig. 1, the valve-piston 53 is moved into position 53a, thereby closing'the V-port 54 and stopping the table movement. A

When thethrottle valve is in a closed position to stop the hydraulic table movement, it is desirable to provide a suitable fluid by-pass whereby fluid may readily pass from the cylinder chamber at one end of the cylinder tothe cylinder chamber at the other end thereof to facilitate a manual traversingmovement of the table. In the preferred construction, a pipe or passage 89 is provided to connect the pipe 44 and the valve chamber 39 with a passage or pipe 8| provided as an extension of the pipe 39. When the throttle valve 59 is in a closed position, as indicated in broken lines, fluid may readily pass from the cylinder chamber 4|, through the pipe 39, the pipe 8|, through a valve chamber 82 between the valve pistons 52 and 53, through the pipe 99, the pipe 44, and into thecylinder chamber 42. This by-pass in the throttle valve interconnects the cylinderchambers 4| and 42 so that when the fluid pressure system is shut ofi by closing the throttle valve 59, the table may be readily moved manually, if desired.

A manually operable table traverse mechanism may be of the type shown in the prior United States Patent No. 2,071,677 and may consist of a In the preferred construction, the end of machine.

desired. In the preferred construction, adjustable table dogs 99 and 9| are adjustably mounted in a T-slot 92 on the table |9. The dogs 99 and 9| are arranged to engage a pin 89 on the upper end of a reverse control lever 93 which is pivotally mounted on a stud 94 on the base 9 of the The lever 93 is operatively connected to move the valve stem 29.

In order that the table may be reversed with a minimum amount of vibration, it is desirable to provide a lost motion connection between the reversing lever 93 and the reversing valve 25, so that during the initial movement of the reverse lever under the influence of the table dogs, the valve is not moved. This mechanism preferably comprises a short lever 95 fixedly keyed to the inner end of the stud 94. A short lever 96 is rotatably mounted on the stud 94 and is supported thereon by means of a bushing, so that the lever 96 is free to oscillate relative to the stud 94. The lever 96 carries a pin 91 engaging a groove 98 in an extended portion of the valve stem 29.

The lever 95 is provided with an.aperture 99. A pin I99 is fixedly mounted to the lever 96 and projects within the aperture 99 in the lever 95. The lower end of the levers 95 and 96 are pro-' vided with enlarged end portions 9| and I92, respectively, each of which is provided with a semi-cylindrical aperture I93 and I94, respectively. A spring I95 is provided within the semicylindrical apertures I93 and I94 and serves to hold the levers normally in a definite alignedrelationship to each other.

Assuming the parts of the reversing mechanism to be in the position illustrated in Fig. 1, the table is moving in a direction toward the left, which movement continues until the reversing lever 93 is moved a sumcient distance to actuate the lever 95 through its lost motion movement until the aperture 99 engages the pin I99. This movement of the lever 95 relative to the lever 96 serves to compress the spring I95 and when the aperture 99 engages the pin I99, continued movement of the table serves to throw the reversing valve stem 29 into a central position, as indicated in Fig. 3,

in which position fluid under pressure is cut oil from opposite sides of the main cylinder I I. The

compression of the spring I95 then tends to move the valve stem 29 toward the right, whichmovement is prevented by a means to be hereinafter described.

When the compression of the spring I95 is re- I leased, it shifts the valve from a central or neutral position so as to uncover a port I H (as indicated in Fig. 3), decreasing the fluid presposite end of the main driving cylinder H and thereby cause the table ID to move in the opposite direction.

Due to the diflerential in the pressure areas bestroke to accomplish the desired results.

tween the valve pistons 30, 34 and 3I, 33, respectively, the chambers I I3 and H2 function as a pilot valve to cause a reversal of the reversing valve under the influence of fluid under pressure. The reversing lever 93 serves only to cause the reversing valve to move to a central or neutral position, as illustrated in Fig. 3, and the spring I05 then under compression serves to move the reversing valve slightly off center to change the respective openings of the ports H0 and I II and cause fluid under pressure to operate through the chambers H2 and H3 to cause a fluid pressure reversal of the reversing valve, thereby combining the functions of a reversing valve and a pilot valve in a single valve unit and eliminating the piping connections and losses due to passages between the various valves as experienced heretofore.

Fluid within the valve chamber II2 may exhaust through a port I and similarly fluid within the valve chamber may exhaust through a P rt II 3, into a port I2I, into reservoirs I22 and I23, respectively. When the valve piston 29 is moved to either end of its stroke, as shown in the diagrammatical illustration in Fig. l, fluid within the chamber H3 is free to exhaust through port I2I, a pipe I24, and through a pipe I25, into the reservoir I23. Similarly, when the valve piston 29 is moved towardthe right, fluid within the valve chamber H2 may exhaust through the port I20, a pipe I26, and a pipe I21, into the reservoir I22.

In a cylindrical grinding operation, it is frequently desirable to provide a sufllcient dwell of the table at the end of its reciprccatory stroke so that the work piece may rotate at least one complete rotation before the table stops its movement in one direction and starts its movement in the reverse direction. The period of dwell necessary to accomplish this result varies with the size of the work being ground, the width of the grinding wheel being used, as well as the relative speeds of the work rotation and table reciprocation. It is, therefore, desirable to provide a variable dwell at either or both ends of the table In the preferred construction, the dwell at the end of the table stroke may be accomplished by interrupting the reversal in movement of the control or reverse valve and allowing it to dwell in a central position for a predetermined time interval.

In the preferred construction an electricalcontrol mechanism is provided for controlling the delayed action of the reversing valve 25 so that a table dwell of any desired length may be ob tained. This is preferably accomplished by providing a cut-oil valve I30 between a pipe I24 and a pipe I25. The valve I30 is preferably a piston type valve, which is normally held open by means of a spring, allowing free passage of fluid from the pipe I24, through a valve chamber I3I, into the pipe I25. The valve I30 is arranged so that it may be automatically closed by means of a solenoid I32. The solenoid is preferably controlled by an adjustable time delay relay I33 which is connected with power lines I34 and is set in motion by a normally open limit switch I35 having an actuating roller I36 arranged in the path of an adjustably positioned arrow point'pro jection I31 carried by a downwardly extending projection of the reversing lever 93.

.Similarly, a cut-off valve I 40 of the piston type is provided which is normally held open by means of a spring so that fluid passing through the pipe I26 may pass directly through a valve chamber I4I into the pipe I21 and return to the reservoir I22. The valve I40 is arranged to be actuated by means of a solenoid I42 which is also controlled by the adjustable electrical time delay relay I33 which, as above described, is set in motion by the normallyopen limit switch I35. The limit switch I35 is instantaneously closed each time the reversing lever 93 is shifted to change the direction of movement of the table III.

The arrow point projectionl31 of the lever I93 may be adjusted longitudinally relative to the i lever 93 by means of an adjusting screw I45 to solenoid I42 is cut in to be actuated by the time delay relay I33. When the switch I46 is rocked in a clockwise direction, the solenoid I32 is cut in so that it may be energized when the circuit is closed by the closing of the switch I35. In order that the proper solenoid valve I32 or I42 may be connected automatically, it is desirable to provide a suitable connection whereby the switch I46 may be automatically actuated in'timed relation with the table movement. This is preferably accomplished by providing a connection between the switch I46 and the reversing lever 93 so that when the reversing lever 93 is shifted either manually or by means of the table dogs 90 or 9i, the switch I46 will be actuated to connect the proper solenoid I32 or I42 with the time delay relay I33 and the power lines I34. This is preferably ac-- complished by means of a connecting link I41 which is connected at one end by means of a stud I48 with the adjustable projection I31 on the lower end of the reversing lever 93. The other end of the link I41 is provided with a yokeshaped projection I49 which has two downwardly projecting arms I50 and I5I which are arranged to actuate the switch I46 and shift it in timed relation with the movement of the reverse lever 93. The yoke-shaped projection I49 is preferably adjustably mounted on the link I41 and each of the arms I50 and I5I is adjustably mounted on said projection so that the time of actuation of I the switch I46 relative to the movement of the reverse lever 93 may be varied as desired.

The operation of this table reciprocating mechanism will be readily apparent from the foregoing disclosure. Assuming all of the parts have been previously adjusted and the table I0 is traversing in the direction of the arrow, namely toward the left (Fig. 1), this movement continues until a projection I on the reversing dog 9I- engagesa pin or stud 89 on the reversing lever 93- When the projection I 55 of the dog 9| engages the pin 69, the continued movement of the table I0 toward the left serves to rock the reversing lever 93 in a counterclockwise direction which serves through the downwardly projecting arm I50 of the yoke I 49 to shift the switch I46 to render the solenoid I32 operative. At the same time, this movement of" the reverse lever in a counterclockwise direction shifts the control valve 29 toward the right (Fig. 1) and the arrow point at the lower end of the projection I31 of the reversing lever 93 engages the roller I36 of the limit switch I35 to close the switch and start the time delay relay I32 in operation. The reversing lever 93 shifts the valve 25 to a central position. The spring I05 is compressed during this movement of the reverse lever and the compressed spring serves to throw the valve 25 slightly beyond its central position. The valve I30, being closed by energizing the solenoid I32, serves to hold the reversing valve 29 in this position due to the fact that fluid within the valve chamber H3 cannot pass out through the pipe Ifit since the solenoid valve Iit is closed. The solenoid I32 remains energized for a predetermined time interval as governed by the adjustable time delay relay I33 so as to cause the table 8 to dwell at the end of its reciprocatory stroke for a predetermined time interval before starting in the reverse direction. After a predetermined set time interval, the time delay relay I33 serves to break the circuit and deenergize the solenoid I 52 which allows the passage of fluid from the valve chamber I3 through pipe 2d, into pipe I25 which returns the fluid into the reservoir I23 at-the end of the control valve 25, thus allowing the reversing valve 29 to shift from a central or neutral position toward the right due to the differential in piston areas between the valve piston 3t and 3t and thereby to reverse the direction of flow of fluid to the cylinder II to start the table I traversing in the reverse direction.

The table It starts moving toward the right, which movement continues until a projection I on the table dog 90 engages the stud 89 on the reversing lever and rocks the reversing lever in a clockwise direction again to shift the control or reverse valve 29 in a direction towards the left (Fig. 1) to stop the table It. During this clockwise movement of the reversing lever 93, thedownwardly extending projection I5I of the yoke I69 engages the switch I66 and shifts it into the position illustrated in Fig. 1 to close the circuit and thereby energize the solenoid Hi2, after which the arrow point projection I 31 on the reversing lever 93 engages the roller I36 of the limit switch I35 again to close the limit switch I35 to set the time delay relay I33 in motion. The energizing of the solenoid m2 closes the valve I ia to prevent fluid from the valve chamber I I2 passing through the pipe I26 into the pipe I21 and returning to the reservoir I22. The solenoid valve I remains closed for a predetermined time interval as governed by the adjustable time delay relay I33 which serves after the set time interval to break the circuit and thereby deenergize the solenoid I 42 whereupon the released compression of a spring serves to open the valve I60 and allow fluid to pass from the valve chamber I I2, through pipe I26 into the pipe I21 which flows into the reservoir I22 at the right-hand end of the valve 25. Due to the differential piston areas between the pistons 33 and 3d, the control valve will then shift from a central or neutral position toward the left to reverse the direction of flow of fluid under pressure to the table cylinder II and thus start the movement of the table It toward the left.

By manipulation of the adjustable time delay relay I33, the dwell at each end of the table stroke may be adjusted as desired, that is so that an equal dwell of a variable extent may be obtained at both ends of the table reciprocation.

It will thus bev seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodimaniac ments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a grinding machine, a longitudinally movable table, means including a piston and cyl: inder to reciprocate said table, a reversing valve therefor, means including a reversing lever to actuate said valve, a pair of independent electrically controlled valves, one of said valves being arranged to control the shifting movement of said reversing valve in one direction and the other of said valves being arranged to control the shifting movement of the reverse valve in the opposite direction, an adjustable time delay relay which is rendered operative by said reversing lever, and means actuated by said reversing lever to render one of said electrically controlled valves operative when the lever is moved in one direction and to render the other control valve operative when the lever is moved in the opposite direction.

2. In a grinding machine, a longitudinally movable table, means including a piston and cylinder to reciprocate said table, a reversing valve therefor, means including a reversing lever to actuate said valve to stop the table movement, a pair of independent solenoid valves, one of which serves to control the shifting movement of said valve in one direction and the other of which serves to control the shifting movement of the reverse valve in the opposite direction, an adjustable time delay relay which is rendered operative by said reversing lever to actuate said solenoid valves, and means including a switch actuated by said reversing lever to render one of said solenoid valves operative when the lever is moved in one direction and to render the other solenoid valve operative when the lever is moved in the opposite direction.

3. In a grinding machine, a longitudinally re ciprocable table, means including a piston and cylinder operatively connected to reciprocate said table, a reversing valve which is arranged to admit fluid under pressure to either end of said cylinder, a pair of adjustable dogs on said table, means including a reversing lever operatively connected to move said valve to a central position when acted upon by one of said dogs, a pair of independent solenoid valves operatively connected with each end of said reverse. valve to prevent movement of the reverse valve beyond a central position, an, electrical switch which is actuated by said reversing lever to close one of said solenoid valves, a time delay relay which is set in motion by said switch to open said solenoid valve after a predetermined time interval, and means including a second switch actuated by said lever to render one or the other of said solenoid valves operative. 4

4. In a grinding machine, a longitudinally reciprocable table, means including a piston and cylinder operatively connected to reciprocate said table, a reversing valve which is arranged to ad mit fluid under pressure to either end of said cylinder, a pair of adjustable dogs on said table, means including a reversing lever operatively connected to move said valve to a central position to stop the table movement when actuated upon by one of said dogs, a pair of independent solenoid valves operatively connected one with each end of said reverse valve to prevent movement of the 20 said table which are arranged to actuate said lereversing valve beyond a central position during a predetermined period of dwell, a limit switch, an adjustable projection on said reversing lever to actuate said switch to close one or the other of said solenoid valves, a time delay relay which is set in motion by the closing or said switch to open said solenoid valve after a predetermined time interval, and means including a second switch actuated by said reverse lever to render one or the other of said solenoid valves operative, depending upon the direction of movement of said reversing lever.

5. In a grinding machine, a longitudinally reciprocable table, means including a piston and cylinder operatively connected to reciprocate said,

table, a reversing valve associated therewith and arranged to admit fluid under pressure to either end of said cylinder, a control valve operatively connected to move said valve, adjustable dogs on ver to shift the reversing valve to a central or neutral position, means including a pair of solenoid controlled valves, one operatively connected with each end of said reversing valve and arranged to prevent shifting of the reverse valve beyond a central or neutral position, a normally open switch actuated by and in timed relation with said control lever, a single electrically oper-' ated time delay relay which is set in motion by the closing of said switch, and means including a double throw switch actuated by said reversing lever operatively to connect either one or the other of said solenoid valves in series with said time delay relay to render one or the other of said solenoid valves operative at each end of the table stroke, said parts being arranged to allow the reverse valve to shift into its reverse position after a predetermined period of dwell.

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